Add CLI-level tests for log and timeline option parsing

[theDakshJaitly]

Follow-up from Copilot review on PR #39.

Problem

mex log / mex timeline have direct module tests, but not enough CLI-level coverage for command wiring and option parsing.

Risky areas called out in review:

• mex log --type invalid type handling
• repeated --file accumulator behavior
• mex timeline --limit parsing via parsePositiveIntArg
• program.parseAsync behavior for the new event-layer commands

Suggested fix

Add a small CLI smoke/unit test that exercises the Commander wiring directly, preferably without depending on a real published binary.

Acceptance criteria

• Valid mex log options are parsed and passed through correctly.
• Invalid --type produces a useful failure.
• Repeated --file values are preserved.
• mex timeline --limit rejects invalid values and accepts positive integers.

Source: #39 (comment)